TheStreet's Jim Cramer says Walmart is a 'dinosaur' compared to online retailers like Amazon. He says Walmart is spending to improve their online shopping experience but at the end of the day 'it's just this thing that lies there.' Cramer says he prefers Amazon but he says the retail sector is a difficult place to invest. Cramer says he, along with Stephanie Link, sold their Action Alerts PLUS positions in Macy's and Costco because retail is 'just a nightmare.' Cramer's advice for investors is to avoid retail at all costs and put their money to work in other sectors.